Tuesday, 29 November 2011

Let’s Make Toy Together

Nowadays, children do not make toys by themselves as toys can be found and bought everywhere.
In my childhood, my parents did not buy any toy for me. I made toys with my own hands. I still remember the toys I made as I was a girl. Here is one of them, let’s try to make it.


In the center of the top of the two cans, make two little holes, through which the ends of the wire can pass. This, tied in a knot, will not come undone even under the light pressure necessary for keeping it tight (as per figure 21). You need an empty space big enough for the wire to be extended its entire length. One person will be on one end with the can at her or his ear and another person will be at the other end with the can to her or his mouth. The conversation can start, with better results if the wire is coated with wax or shoe polish.

Boys and girls,
do you know the tools, mechanics and physical principles applied in this handmade toy telephone?

If yes, do leave your answer in the comment colume.

Sunday, 27 November 2011

Modern Myths Taught As Science

Recently, I have found an interesting website discussing the myths taughts as science. I hereby  share with you some misconceptions in science text books, and other presumably authoritative sources.  It is extremely difficult to “unteach” ideas which have been learned and reinforced in earlier years.
These myths originate from failure to understand the concepts behind factoids that have been memorized from time to time, and lack of effort to attempt to connect the pieces together to form a unified, overall scheme. 

Students need to be made aware that they are learning a simple framework into which the details can be fit later.  Exposing students to a level a bit beyond that which they are expected to master, is not a bad idea.

Example 1 of misconceptions -
The taste map of the tongue
Many life science books contain a drawing of a tongue with different regions marked, sweet, bitter, sour, and salty.  It should not be difficult for a student to design an experiment to test this hypothesis. Any of the tastes can be detected by any of the regions.  According to David V. Smith and Robert F. Margolskee, ("Making Sense of Taste", Scientific American, March 2001) this myth started as a misinterpretation of research reported in the late 1800's.

Example 2 of misconceptions  -
We get heat from Sun

Indirectly, we might be able to claim that Earth receives heat from Sun, but not as students understand the statement.  Radiant heat is a 19th century concept.  Remember, “Heat is the energy of the random motion of the particles in matter.”  Where there are no particles of matter, there can not be any heat.  “Radiant heat” is an obsolete name for infrared radiation, a kind of electromagnetic energy.  Like all other electromagnetic radiation from Sun (or any other source), radio, microwave, infrared, light, ultraviolet, x-ray, cosmic ray, infrared radiation absorbed by matter (Earth included) is changed into heat energy in the matter.  At the same time, heat in matter is being converted to electromagnetic energy, and radiated away.  Which is why the ground cools at night.

Example 3 of misconceptions  -
Columbus proved that Earth is round

Most of us are familiar with story of Columbus’s arguing with learned professors about the shape of Earth.  He saying it is round and he could sail west to Japan, and they saying if he sailed far enough he would fall off the edge of the world.  This mythapparently started with a biography of Columbus which became popular in the early 19thcentury.

In fact, about 1500 years before Columbus was born, the diameter of Earth was accurately measured by Eratosthenes of Alexandria (c. 276 B.C. - c. 194 B.C.). For centuries before Columbus, every school boy knew that “Earth is a sphere set at the center of the universe.”  The problem was that Columbus had gotten hold of a mistranslation ofEratosthenes’ work, and believed Earth to be much smaller than it is.  So he insisted hecould sail west to Japan. 
The learned professors said his crew would starvebecause the ships couldn’t carry enough food for so long a voyage.  The professors were right.However, because of the unexpected intervention of the Americas less than half way toJapan, Columbus became a hero.  And to his dying day he was convinced that he hadvisited the islands of Japan.
For more information, kindly visit to Modern Myths Taught As Science by Kenneth Fuller at  http://learn-science.20m.com/tmyths.htm